Engine.



No. 7l0,|36. Patented Sept. 30, I902.

W. A. BOLE.

ENGINE.

[Application filed Aug. 16, 1897.)

(No Model.)

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UNITED STATES 'AATENT OFFICE,

\VESTINGHOUSE SYLVANIA.

MACHINE COMPANY, A CORPORATION OF PENN- ENGINE.

SPECIFICATION forming part of Letters Patent'No. 710,136, dated. September 30, 1902.

Application filed August 16, 1897. berial No. 648,385. (No model.)

To all whom it may concern.-

Be it known that I, WILLIAM A. BOLE, a citizen of the United States, residing at Pittsburg, in the county of Allegheny and State of Pennsylvania, haveinvented or discovered a certain new and useful Improvementin Engines, of which improvement. the following is a specification.

The object of my invention is to provide an improvement in gas, air, or steam engines or pumps; and to this end myinvenlion con-' sists in means for preventing the passage of oil around the piston of an engine or pump, as hereinafter set forth.

In the accompanying drawings, which illus-- case the crank-case is usually partly filled with water and oil, and the piston and cylinder of the engine are lubricated by the oil, which is splashed up or thrown into the cylinder or on the piston, and in case the pressure in the cylinder between the piston and the cylinder-head is at any time in the cycle of operation less than the pressure in the crankcase oil is liable to be forced past the piston into the cylinder and to accumulate on the head of the piston and other parts and in the clearance-spaces of the engine. For various reasons this may be objectionablein any kind of engine or pump; but it is particularly objectionable in explosive or internal-combustion gas-engines, in which the degree of heat is so great that the oil is evaporated and leaves a deposit in the form of a powder or incrustation on the walls of the cylinder and on the piston and valves and valve-seats.

In Fig. 1 of the drawings I have shown a central section through the cylinder 1 of a vertical gas-engine provided with a-waterjacket 2 and with a jacketed head The cylinder 1 is mounted on a closed crankcase 4:, a portion only of which is shown in the drawings. The piston 6 is connected, by

means of a connecting-rod 5, with the crank on the main shaft, (not shown) and the oil which is thrown up into the cylinder 1 serves as a lubricant between the piston 6 and thecylinder.

\.Vhen the piston (3 of agas-engine not provided with my improvement is making its charging strokethat is, when it is by its downward or outward movement drawing in the charge of mixed air and gasthe prescylinder and clearance-spaces, on the valves' and valve-seats, and on the igniting devices. This residue may bein the form of a powder deposited on the surfaces of the parts or floatingin theinterior of the clearance-spaces and passages, or it may be in the form of a flaky or granular incrustation; but in any form it is very objectionable, since it covers parts which should be kept clean and bright.

The sparking-points or incandescent portions of igniting devices may become so coated with the residue in the form of powder or in some other form that the efficiency of the igniter may be seriously affected or its proper action altogether prevented, and the proper seating of the valves may be prevented and the wear of the valves and valve-seats greatly increased by the cutting action of the deposit, which is usually of great hardness.

In case the particles are of considerable size they may, when caught on a valve-seat, prevent the closing of the valve and interfere with the proper operation of the engine. Particles which are being discharged through the exhaust-passages are thus liable to prevent the complete closure of the exhaustpassage, in which case the desired compression of the charge may be prevented or seriously interfered with.

The oil which covers the outer surface of the piston and fills the thin annular space between the piston and the inner surface of the cylinder will tend, during a charging stroke of the engine, to move up into the cylinder under the pressure in the crank-case, and when no considerable difference of pressure exists on the opposite sides of the piston the reciprocating movement of thepiston will tend to carry oil into the cylinder. The considerable length of the trunk-piston interferes with the effect which the higher pressures in the cylinder during the compression and working strokes might have in preventing or hindering the movement of the oil into the cylinder.

In order to prevent or hinder the passage of oil in too great quantity into that portion of the cylinder between the piston and the cylinder-head and its accumulation on the piston and other parts and the formation and accumulation of the residue or incrustation referred to, I provide grooves 8 on the outer cylindrical surface of the piston and also provide passages 9, leading from the grooves S into the interior of the piston,w hich is open to the crank-case. The oil in its movement toward the interior of the cylinderthat is, away from the crank-case-collects in the grooves S, and the form of the groove 8 is such as to assist the trapping of oil in the grooves either by permitting an easy flow of the oil into the groove over the inclined surface 10 or by the action of the rectangular edge 11 of the groove in sweeping the oil from the inner surface of the cylinder as the piston moves toward the cylinder-head. The oil which is trapped in the groove 8 is free to flow into the interior of the piston through the passages 9 and to be returned to the crankcase. I

I have shown one of the grooves 8 near the crank end of the trunk-piston 6 and the other some distance from the other end; but my ciently lubricated and but a small quantity of oil is deposited on the head of the piston. It will be obvious that the form of the groove on the surface of the piston may be varied and that a very slight depression may in many instances be employed, or that the passages 9 may to a certain extent perform the desired function of returning oil to the crank-case without the employment of a groove on the surface of the piston, or the grooves 8 may extend only apart of the way around the pistonthat is, they need not be continuous. It will also be obvious that the employment of the groove 8 for other or additional purposes need not interfere with its function as described. For example, a

groove containing a packing-ring and connected with a space opening to the crank-case may be employed if the formation'of the groove and ring are such as to permit the admission of oil to the groove and to the passages 9 leading therefrom.

I claim as my invention and desire to secure by Letters Patent- 1. The combination with a cylinder,of a piston adapted to work therein and provided with means for permitting the free escape of oil from the space between the cylinder and piston through the latter below its head in all of its positions, substantially asset forth.

2. The combination witha cy1inder,of apiston having a groove or grooves and a passage or passages extending therefrom to the interior and below the piston-head for discharging oil from between the piston and cylinder and for preventing or hindering the passage of oil to the head of the piston or to the space between the piston and the cylinderhead, substantially as set forth.

3. The combination with a cylinder and a crank-case, of a piston adapted to work in the cylinder, and having a free passage or passages extending inward from its periphery to the space below its head, through which oil may flow from the space between the piston and cylinder to the crank-case or to a space communicating therewith, substantially as set forth.

4. The combination with a crank-case, of a cylinder connected with and opening into the crank-case and a trunk-piston adapted to work in the cylinder, and having a circumferential groove and a free passage, or passages, leading from the groove into the interior of the piston below its head, whereby oil may pass freely from the space between the cylinder and piston to the interior of the crankcase, substantially as set forth.

5. In an engine, the combination with a closed crank-case and a cylinder, of a piston operating in said cylinder and provided with one or more external, circumferential grooves having a downwardly and inwardlyinclined upper side and one or more passages leading from the inner edge of said groove to the interior of the piston.

6. In an engine, the combination with a closed crank-case and a cylinder, of a piston operating in said cylinder and provided with ICC an external, circumferential groove having an inwardly and downwardly inclined upper 

